全文获取类型
收费全文 | 1147篇 |
免费 | 63篇 |
国内免费 | 1篇 |
出版年
2023年 | 8篇 |
2022年 | 13篇 |
2021年 | 23篇 |
2020年 | 15篇 |
2019年 | 23篇 |
2018年 | 27篇 |
2017年 | 30篇 |
2016年 | 34篇 |
2015年 | 42篇 |
2014年 | 48篇 |
2013年 | 77篇 |
2012年 | 90篇 |
2011年 | 74篇 |
2010年 | 54篇 |
2009年 | 31篇 |
2008年 | 50篇 |
2007年 | 67篇 |
2006年 | 44篇 |
2005年 | 49篇 |
2004年 | 39篇 |
2003年 | 36篇 |
2002年 | 29篇 |
2001年 | 31篇 |
2000年 | 31篇 |
1999年 | 17篇 |
1998年 | 10篇 |
1997年 | 8篇 |
1996年 | 9篇 |
1995年 | 5篇 |
1994年 | 7篇 |
1992年 | 13篇 |
1991年 | 6篇 |
1990年 | 8篇 |
1988年 | 7篇 |
1987年 | 11篇 |
1986年 | 5篇 |
1985年 | 11篇 |
1984年 | 8篇 |
1981年 | 5篇 |
1979年 | 14篇 |
1978年 | 10篇 |
1977年 | 5篇 |
1975年 | 6篇 |
1974年 | 7篇 |
1973年 | 6篇 |
1972年 | 9篇 |
1971年 | 6篇 |
1970年 | 6篇 |
1969年 | 16篇 |
1967年 | 8篇 |
排序方式: 共有1211条查询结果,搜索用时 15 毫秒
1.
Meiosis was studied in control and seed-irradiated materials of Lactuca sativa, cultivars Tom, Cos and Webbs, L. serriola from the wild, and Cichorium intybus. In meiosis of the M1 plants from irradiated seed, observations of univalent and multivalent formation, bridge formation at Anaphase I and II, micronucleus formation and persistence, and pollen fertility, were carried out, and compared with controls. Quantitative estimations of bridge formation were made in L. sativa Tom and Cos and in L. serriola, at anaphase I only. It was found that the frequency of anaphase I bridges and reduction of pollen fertility in the M1 and also M2 generation, were different for each variety or species; these could be sequenced radiation-resistant to sensitive in the order Tom, Cos and L. serriola. 相似文献
2.
3.
4.
5.
D Kierek-Jaszczuk M Zurkowski E Sk?adanowska-Krzyzanowska K Tomaszewska-Guszkiewicz 《Animal blood groups and biochemical genetics》1979,10(1):15-18
Genetic variants of serum alkaline phosphatase were studied by the method of starch gel electrophoresis in the Z?otnicka Pstra breed of pigs. Two regions of alkaline phosphatase migration were observed. A single fraction in region I and four different phenotypes: AB, B, BC and BD in region II, were found. For AB, B and BC phenotypes the genetic control by three alleles AkpA, AkpB and AkpC is suggested. The observed segregation ratios in some cases deviated significantly from the expected ones. 相似文献
6.
T Skórski M Kawalec J Kawiak 《Folia histochemica et cytobiologica / Polish Academy of Sciences, Polish Histochemical and Cytochemical Society》1987,25(1):23-27
The composition of peritoneal exudate and spleen cells of CD2F1 mice after fourfold i.p. administration of L 1210 leukemia cells treated with cyclophosphamide (L 1210-CY cells) were examined. The number of cells in peritoneal cavity did not increase, however, the spleen weight rose after administration of L 1210-CY cells. The per cent of lymphocytes T was increased 2.5 times but the content of macrophages and lymphocytes B was normal in the peritoneal cavity after L 1210-CY cells injections. In the spleen an 1.4 times increase of the per cent of lymphocytes B, but normal level of macrophages and lymphocytes T were observed. 相似文献
7.
8.
Sarah Perreault M. Ather Ali Skúli Skúlason David L. G. Noakes 《Environmental Biology of Fishes》1990,27(2):131-137
Synopsis At high latitudes, such as in Iceland, the daily photoperiod varies from almost continuous darkness in winter to virtually constant light in summer. Previous studies of detailed retinal structure in vertebrates have shown significant daily and annual effects of photoperiod. We sampled arctic charr in Iceland during the summer, including fish that were both light- and dark-adapted, during both day and night. We observed retinomotor responses characteristic of light- and dark-adaptation, but found no difference in the number of synaptic ribbons in the retina. The morpho-physiological changes, appearing as retinomotor responses, are thus not expressed at the synaptic level. 相似文献
9.
Multiple shoot formation and their elongation from excised apical vegetative shoots of a 40-year old-tree ofMitragyna parvifolia Korth. was achieved in Murashige and Skoog's medium supplemented with 4.44 M benzyl adenine. The in vitro regenerated shoots rooted when cultured on modified Murashige and Skoog's medium containing low inorganic salts and the three auxins. Regeneration by this method was suitable for mass propagation of the plant. 相似文献
10.
Summary The incorporation of C14-amino acids (aspartic acid, glutamic acid, threonine and proline) and C14-nucleic acid bases (adenine, guanine, cytosine and uracil) into the seedling, reproductive stage and young ear portion of
rice plant was investigated.
It was found that C14-aspartic acid was incorporated into the rice seedling more rapidly than C14-threonine or C14-proline; on the other hand C14-proline was found to be more rapidly incorporated than C14-aspartic acid into reproductive stage plant and young ear portion.
Similarly C14-adenine was incorporated into the rice seedling more rapidly than other C14-labelled bases. On the other hand C14-uracil was preferentially incorporated to C14-adenine or C14-guanine into the reproductive stage plant and young ear portion.
It is suggested from the results obtained that proline is polymerized into polypeptide or protein in the rice plant more rapidly
at the reproductive stage than at the seedling stage and that a higher proportion of pyrimidine bases might be involved into
the metabolic process at the reproductive stage of rice plant. 相似文献